Radio access system and portable terminal device

ABSTRACT

As a result of ISR being enabled between a portable terminal device and a network which are capable of communicating by using the communication protocols of a plurality of wireless access technologies, the portable terminal device performs position registration processing between the plurality of wireless access technologies and the portable terminal device each time a fixed period of time elapses, and the portable terminal device is able to move between the plurality of wireless access technologies that have already been registered, without conducting new position registration processing. At this time, if there is a possibility of there being a difference in ISR states (activated or not activated) between the portable terminal device and the network, the portable terminal device ignores any instructions issued by the network for ISR to be enabled in the portable terminal device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.16/182,383 filed Nov. 6, 2018, which is a Continuation of U.S.application Ser. No. 15/893,888 filed Feb. 12, 2018 and issued as U.S.Pat. No. 10,154,451 on Dec. 11, 2018, which is a Continuation of U.S.application Ser. No. 15/004,011 filed Jan. 22, 2016 and issued as U.S.Pat. No. 9,936,446 on Apr. 3, 2018, which is a Continuation of U.S.application Ser. No. 14/637,520 filed Mar. 4, 2015 and issued as U.S.Pat. No. 9,282,526 on Mar. 8, 2016, which is a Continuation of U.S.application Ser. No. 14/144,727 filed on Dec. 31, 2013 and issued asU.S. Pat. No. 9,084,219 on Jul. 14, 2015, which is a Continuation ofU.S. application Ser. No. 13/642,882 filed Nov. 26, 2012 and issued asU.S. Pat. No. 8,655,359 on Feb. 18, 2014, which is a U.S. national stageof application No. PCT/JP2011/059413 filed on Apr. 15, 2011, whichclaims priority from Japanese Patent Application No. 2010-102860, filedon Apr. 28, 2010, the disclosures of all of which are incorporatedherein by reference.

TECHNICAL FIELD

The present invention relates to a portable terminal device such as amobile phone and the like, and especially relates to a radio accesssystem and a portable terminal device that support a communicationsystem in relation to a plurality of radio access technologies (RATs).

BACKGROUND ART

In a communication system defined as Long Term Evolution (LTE) orEvolved Universal Terrestrial Radio Access (E-UTRA) in Third GenerationPartnership Project (3GPP) standardization, a function called “Idle modeSignaling Reduction (ISR)” is introduced in order to reduce a frequencyof location registration processing that occurs in relationship with anetwork when a portable terminal device, being compatible with acommunication system (such as Global System for Mobile communications(GSM), Universal Mobile Telecommunications System, and the like) inrelation to a plurality of RATs, moves among different RATs. When ISR isactive, the portable terminal device holds both a location registrationinformation parameter related to GSM or UMTS and a location registrationinformation parameter related to LTE, both the location registrationinformation parameters being received from the network. Then, theportable terminal device becomes ready to move between a GSM/UMTS areaand an LTE area, for both of which location registration processing hasalready been carried out, without location registration processing withthe network.

General descriptions on ISR are defined in non-patent literatures NPL1to NPL3 that are specifications of 3GPP.

CITATION LIST Non-Patent Literature

NPL1: TS23. 401: General Packet Radio Service (GPRS) enhancements forEvolved Universal Terrestrial Radio Access Network (E-UTRAN) access(http://www.3gpp.org/ftp/Specs/html-info/23401.htm)

NPL2: TS24. 301: Non-Access-Stratum (NAS) protocol for Evolved PacketSystem (EPS); Stage 3(http://www.3gpp.org/ftp/Specs/html-info/24301.htm)

NPL3: TS24. 008: Mobile radio interface Layer 3 specification; Corenetwork protocols; Stage 3(http://www.3gpp.org/ftp/Specs/html-info/24008.htm)

SUMMARY OF INVENTION Technical Problem

Incidentally, if once an instruction on ISR activation is provided in anISR function of 3GPP from a network after expiration of a locationregistration cycle timer owned by a portable terminal device, thereaftersometimes the portable terminal device does not start an ISRinactivation timer so that ISR remains activated. In this case, therearises a situation of conflict; namely the network operates on thepremise of ISR being inactivated, meanwhile the portable terminal deviceoperates on the premise of ISR being activated.

That is because each of the portable terminal device and the network hasa location registration timer individually for synchronizing the statusof location registration, and both the timers are not completelyidentical with each other, and specifically the timer that the networkhas is set to be longer in accordance with specifications.

Moreover, under conditions where arises the situation of conflict withrespect to ISR between the network and the portable terminal device, ifthe portable terminal device moves into an area with a different RAT andthen location registration processing is carried out, the networkbecomes unable to take over the location registration information of theportable terminal device between the areas of the different RATs.

That is because, in the case where the portable terminal device movesbetween areas in such a way as to cross over RATs, a terminal-specificidentifier to be specified for a location registration requestingmessage, which the portable terminal device sends to the network,becomes different, depending on whether ISR is active or inactive(wherein, the identifier being one of Globally Unique TemporaryIdentifier (GUTI), Packet Temporary Mobile Subscriber Identity (P-TMSI),and the like). If the portable terminal device sends a locationregistration requesting message on the basis of ISR being active underconditions where arises the situation of conflict with respect to ISRbetween the network and the portable terminal device, the locationregistration information from the RAT before moving between the areascannot be taken over inside the network in accordance withspecifications in 3 GPP.

Moreover, in the case where, even after the portable terminal devicemoves into an area with a different RAT and then location registrationprocessing is carried out, the network still cannot take over thelocation registration information of the portable terminal devicebetween the areas of the different RATs, the portable terminal device islikely to receive an unnecessary request on releasing registration fromthe network.

That is because, in the case where the network cannot take over thelocation registration information of the portable terminal devicebetween the areas of the different RATs, the network is allowed torequest the portable terminal device to once release the registrationand carry out again location registration processing, as the network'soperation, in order to obtain correct location registration informationof the portable terminal device.

Thus, it is an object of the present invention to give solutions for thesubjects described above, and to provide a radio access system and aportable terminal device that can prevent in advance the situation ofconflict with respect to ISR with the network.

Solution to Problem

According to a first aspect of the present invention, provided is aradio access system, including: carrying out location registrationprocessing by a portable terminal device with a plurality of radioaccess technologies, at every time after a certain time period passes byway of activating ISR (Idle mode Signaling Reduction) between theportable terminal device and a network, which are able to communicatewith each other through a communication system in relation to theplurality of radio access technologies; and enabling the portableterminal device to move without newly carrying out location registrationprocessing between radio access technologies for which locationregistration has already been carried out; wherein, under conditionswhere the portable terminal device and the network hold the potential tohave individually different status on whether the ISR is active orinactive, even if the network gives the portable terminal device acommand to activate the ISR, the portable terminal device ignores thecommand.

It is preferable that, without carrying out location registrationprocessing for a radio access technology having had locationregistration up to the time even after a passage of the certain timeperiod, if the portable terminal device carries out locationregistration processing for another radio access technology under asituation where the ISR is inactive, the portable terminal device keepsthe ISR being inactive, even though the network gives the portableterminal device a command to activate the ISR.

It is preferable that, in the case where the portable terminal devicemoves to the radio access technology having had location registration upto the time, after carrying out location registration processing for theother radio access technology, in order to carry out locationregistration processing, the portable terminal device requests thenetwork to carry out location registration processing under conditionsof a setup in which the network can take over location registrationinformation between the other radio access technology and the radioaccess technology having had location registration up to the time.

Moreover, even in the case where the portable terminal device cannotcarry out location registration processing for a radio access technologyhaving had location registration up to the time, even after a passage ofthe certain time period under a situation where the ISR is active, ifthe ISR cannot be inactivated after a predetermined time periodfollowing the passage of the certain time period, even though thenetwork gives the portable terminal device a command to activate theISR, the portable terminal device may ignore the command.

According to a second aspect of the present invention, provided is aradio terminal device, including: a radio unit that can communicate viaradio waves with a network by means of a communication system inrelation to a plurality of radio access technologies; and acommunication controller for controlling communication by the radio unitwith respect to each of the plurality of radio access technologies;wherein, the communication controller carries out location registrationprocessing with the network, with respect to each of the plurality ofradio access technologies; the communication controller executes ISR insuch a way as to enable moving without newly carrying out locationregistration processing between radio access technologies for whichlocation registration has already been carried out; and under conditionswhere the communication controller and the network hold the potential tohave individually different status on whether the ISR is active orinactive, even if the network gives a command to activate the ISR, thecommunication controller ignores the command.

Advantageous Effect of Invention

According to the present invention, it is possible as an effect toprevent in advance the situation of conflict with respect to ISR withthe network.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing that shows a configuration example of a portableterminal device to be used in a radio access system, together with anexample of the use of the radio access system according to an exemplaryembodiment of the present invention.

FIG. 2 is a diagram for explaining requirements of 3GPP specifications,and it is also a sequence diagram that shows an example of operations ofthe portable terminal device and the network.

FIG. 3 is a sequence diagram that shows an example of operations of theportable terminal device and the network shown in FIG. 1.

FIG. 4 is a sequence diagram that shows an example of operations of theportable terminal device and the network, with respect to an operationof an ISR inactivation timer to be used by ISR.

DESCRIPTION OF EMBODIMENTS

An exemplary embodiment of the present invention is explained below indetail with reference to the accompanied drawings.

FIG. 1 is a drawing that shows a configuration example of a portableterminal device to be used in a radio access system, together with anexample of the use of the radio access system according to an exemplaryembodiment of the present invention. The drawing explains the contentsas described below.

A portable terminal device 1 and a network 2 can communicate with eachother by means of a communication system in relation to a plurality ofRATs. In an example explained here, used as two RATs are E-UTRAN (LTE)and GERAN/UTRAN (GSM EDGE Radio Access Network/Universal TerrestrialRadio Access Network).

ISR is activated between the portable terminal device 1 and the network2, and then the portable terminal device 1 carries out locationregistration processing every time when a certain time period has passedin relation to the plurality of RATs. As a result, the portable terminaldevice 1 becomes movable between the RATs, for which locationregistration processing has already been carried out, without newlycarrying out location registration processing. Incidentally, a system isconfigured in such a way that; under conditions where the portableterminal device 1 and the network 2 hold the potential to haveindividually different status on whether ISR is active or inactive, evenif the network 2 gives the portable terminal device 1 a command toactivate ISR, the portable terminal device 1 ignores the command.

The portable terminal device 1 includes: a radio unit 3 that cancommunicate via radio waves with the network 2 by means of acommunication system in relation to a plurality of RATs; and acommunication controller 4 for controlling communication by the radiounit 3 with respect to each of the plurality of RATs. The portableterminal device 1 further includes: a main controller 5 for controllingoperations of the radio unit 3 and the communication controller 4; and amemory 6 for saving information instructed from the main controller 5,and dealing with reading and writing operations.

The communication controller 4 includes: an LTE controller 7 forcontrolling a connection with E-UTRAN; and a 2G/3G controller 8 forcontrolling a connection with GERAN/UTRAN; wherein E-UTRAN andGERAN/UTRAN being inside the network 2 as a counterpart.

The LTE controller 7 includes an LTE transmit-receive controller 9 andan LTE transmit-receive processing section 10. Being configured withcommunication control software, the LTE transmit-receive controller 9controls messages and data to be transmitted to, and received from thenetwork 2 as a counterpart. The LTE transmit-receive processing section10 converts the messages and data to be transmitted to, and receivedfrom the network 2 as a counterpart, between one format with which theLTE transmit-receive controller 9 deals and the other format with whichthe radio unit 3 deals.

The 2G/3G controller 8 includes a 2G/3G transmit-receive controller 11and a 2G/3G transmit-receive processing section 12. Being configuredwith communication control software, the 2G/3G transmit-receivecontroller 11 controls messages and data to be transmitted to, andreceived from the network 2 as a counterpart. The 2G/3G transmit-receiveprocessing section 12 converts the messages and data to be transmittedto, and received from the network 2 as a counterpart, between one formatwith which the 2G/3G transmit-receive processing section 12 deals andthe other format with which the radio unit 3 deals.

In order to control the communication by the radio unit 3, thecommunication controller 4 manages the following information:

-   -   Status of ISR (active/inactive) (to be managed with Temporary        Identity used in Next update (TIN) as an internal parameter of        the portable terminal device, in 3GP);    -   Location registration information for the LTE network (TAU        Periodic Timer, E-UTRAN deactivate ISR timer, Globally Unique        Temporary Identifier (GUTI), and so on); and    -   Location registration information for the GERAN/UTRAN network        (RAU Periodic Timer, GERAN/UTRAN Deactivate ISR timer, Packet        Temporary Mobile Subscriber Identity (P-TMSI), and so on).

FIG. 2 is a diagram for explaining requirements of 3GPP specifications,and it is also a sequence diagram that shows an example of operations ofthe portable terminal device 1 and the network 2.

In this case, it is assumed that ISR is inactive in initial condition ofthe portable terminal device 1 (Step S1). It is assumed that an LTEnetwork 21 in the network 2 holds location registration information ofthe portable terminal device 1 at the time (Step S2). This assumptionmeans that, by that time, the portable terminal device 1 hassuccessfully carried out location registration processing for the LTEnetwork 21. In the meantime, it is assumed that a GERAN/UTRAN network 22in the network 2 does not hold location registration information of theportable terminal device 1 at the time (Step S3). This assumption meansthat, at the time, location registration processing by the portableterminal device 1 is not yet carried out for the GERAN/UTRAN network 22.

It is specified in 3GPP that, after a certain time period passes withthe location registration being once carried out, the portable terminaldevice 1 tries to carry out again location registration processing forthe network 2. The passage of the certain time period is detected bymeans of expiration of a location registration cycle timer (TrackingArea Update (TAU) Periodic Timer, Routing Area Update (RAU) PeriodicTimer, and so on) in the communication controller 4. In the exampleshown in FIG. 2, the expiration of TAU Periodic Timer is detected. Whenthe location registration cycle timer (TAU Periodic Timer) expires (StepS4), it is requested to start location registration processing, such asTAU. Unfortunately, under conditions that location registrationprocessing cannot get started, for example, in the case of beingpositioned outside an LTE area, the location registration processingdoes not get started. In this case, it is specified in 3GPP that, thelocation registration processing does not get started, until a situationallows it to start next time.

Under the condition, the portable terminal device 1 moves into an areaof the GERAN/UTRAN network 22 so as to be located inside a GERAN/UTRANarea (Step S5). The portable terminal device 1 sends a locationregistration requesting message, such as RAU REQUEST, for startinglocation registration processing, such as Routing Area Update (RAU), tothe GERAN/UTRAN network 22 (Step S6). In response, the GERAN/UTRANnetwork 22 sends a message (such as RAU ACCEPT) expressing that therequest from the portable terminal device 1 has been accepted. By makinguse of a parameter in the message, the network 2 gives the portableterminal device 1 a command to activate ISR (Step S8).

In the example shown in FIG. 2, although the location registration cycletimer on a side of the portable terminal device 1 expires at Step S4,location registration for the LTE network 21 is not yet carried out inthe situation. Under the situation, as far as a location registrationcycle timer (such as Mobile reachable timer) that a side of the LTEnetwork 21 owns has not yet expired, the LTE network 21 assumes thatlocation registration is still active. Accordingly, there is a chancethat the GERAN/UTRAN network 22 assumes the location registration beingin successful condition (Step S7), and both the LTE network 21 and theGERAN/UTRAN network 22 are under a situation where the locationregistration is successful so that the network 2 recognizes ISR to beactive. Nevertheless, as a matter of fact, after the locationregistration processing of Step S6, the location registration cycletimer of the LTE network 21 expires (Step S10), the locationregistration information that the LTE network 21 owns about the portableterminal device 1 is released (Step S11). At the time, although the sideof the network 2 recognizes ISR to have been inactivated, the side ofthe portable terminal device 1 recognizes ISR to be active in accordancewith the command from the GERAN/UTRAN network 22 (Step S8) in thelocation registration processing at Step S6. As a result, there arises asituation of conflict with respect to ISR between the portable terminaldevice 1 and the network 2.

Furthermore, under conditions where arises a situation of conflict withrespect to ISR between the portable terminal device 1 and the network 2,even if the portable terminal device 1 moves into a previous RAT (theLTE network 21 in the case of FIG. 2) and attempts to carry out locationregistration processing on the basis of ISR being active (Step S12), thenetwork 2 cuts off the processing (Step S13). That is because aterminal-specific identifier specified for a location registrationrequesting message, to be sent by the portable terminal device 1 to thenetwork 2, has a conflict on whether ISR is active or inactive, and thenthe location registration information from the RAT before moving betweenthe areas cannot be taken over inside the network 2 in accordance withspecifications in 3 GPP.

FIG. 3 is a sequence diagram that shows an example of operations of theportable terminal device 1 and the network 2 shown in FIG. 1. In thisexample of operations; without carrying out location registrationprocessing for a RAT having had location registration up to the time(E-UTRAN (LTE) in this case) even after a passage of a certain timeperiod, if the portable terminal device 1 carries out locationregistration processing for another RAT (GERAN/UTRAN) under a situationwhere ISR is inactive, the portable terminal device 1 keeps ISR beinginactive, even though the network 2 gives the portable terminal device 1a command to activate ISR.

In other words, after operation proceeds up to Step S6 in the samemanner as shown in FIG. 2, even in the case where the network 2 gives acommand to activate ISR in location registration processing at Step S6,the portable terminal device 1 does not activate ISR and just leaves ISRinactive (Step S21).

Thus, when the portable terminal device 1 moves afterwards into an areaof the LTE network 21 (Step S9), and sends a location registrationrequesting message, such as TAU REQUEST, in order to carry out locationregistration processing for the LTE network 21, a terminal-specificidentifier to be specified at the time is for ISR being inactive (StepS22). At the time, the portable terminal device 1 notifies the LTEnetwork 21 that it is needed to take over the location registrationinformation that the GERAN/UTRAN network 22 owns. Therefore, the LTEnetwork 21 can take over the location registration information held atStep S7, from the GERAN/UTRAN network 22 (Step S23). If once thelocation registration information is successfully taken over, ISRbecomes active at the side of the network 2 so that a messagetransmitted from the LTE network 21 to the portable terminal device 1also notifies of ISR being active (Step S24). Receiving the message, theportable terminal device 1 activates ISR (Step S25).

In the above description, explained for example is a case where alocation registration cycle timer for the LTE network 21 expires, andthe location registration information is taken over from the GERAN/UTRANnetwork 22 to the LTE network 21. In an opposite manner, it is alsopossible that a location registration cycle timer for the GERAN/UTRANnetwork 22 expires, and the location registration information is takenover from the LTE network 21 to the GERAN/UTRAN network 22.

Furthermore, even without setting ISR inactive actually in the portableterminal device 1 at Step S21, by way of specifying theterminal-specific identifier with ISR being inactive for the network 2at Step S22, it also becomes possible to have the portable terminaldevice 1 practically ignore activation of ISR from the network 2.

FIG. 4 is a sequence diagram that shows an example of operations of theportable terminal device 1 and the network 2, with respect to anoperation of an ISR inactivation timer to be used by ISR.

It is assumed that; under a situation where ISR is active, ISR is activein the portable terminal device 1 (Step S31), the LTE network 21 ownslocation registration information of the portable terminal device 1(Step S32), and the GERAN/UTRAN network 22 also owns the locationregistration information of the portable terminal device 1 (Step S33).Under the situation described above; in the case where no locationregistration processing can start because of, e.g., being positionedoutside an LTE area, even though a location registration cycle timer ofthe portable terminal device 1 expires after a certain time period haspassed (Step S34) so that the location registration processing cannotget started, there starts an ISR inactivation timer (E-UTRAN deactivateISR timer (T3423), and GERAN/UTRAN Deactivate ISR timer (T3323) aredefined in 3GPP) (Step S35). When the ISR inactivation timer expiresafter a certain time period has passed (Step S37), the portable terminaldevice 1 puts ISR into status of inactivation (Step S38). Furthermore,when a location registration cycle timer expires also at the LTE network21 (Step S39), the location registration information of the portableterminal device 1 is released (Step S40). Even when ISR at the side ofthe network 2 gets into status of inactivation in this way, it isdefined in accordance with specifications in 3 GPP that ISR isconsistently in status of inactivation in both the portable terminaldevice 1 and the network 2.

Nevertheless, if the portable terminal device 1 cannot execute a processof inactivating ISR, the portable terminal device 1 has ISR still instatus of activation, and meanwhile the network 2 has ISR in status ofinactivation. As a result, there arises a situation of conflict withrespect to ISR.

Therefore, it is ensured that; even if a command for activating ISR isgiven from the network 2, the portable terminal device 1 ignores thecommand under conditions where the ISR inactivation timer cannot getstarted. In this context, the “conditions where the ISR inactivationtimer cannot get started” include, for example, a situation in which thelocation registration cycle timer (such as T3412) has already expiredeven though the network gives a command to activate ISR.

According to the embodiment of the present invention as explained above;even if the location registration cycle timer expires under conditionswhere ISR is not active, and afterwards the network 2 gives a command toactivate ISR with respect to the location registration carried out in adifferent RAT, operation progresses in such a way that the portableterminal device 1 ignores the command so as not to activate ISR.Accordingly, even in the case where, with ISR not being in status ofactivation, the network 2 gives a command to activate ISR after thelocation registration cycle timer owned by the portable terminal device1 expires, it becomes possible to prevent beforehand a situation ofconflict with respect to status of ISR from arising between the portableterminal device 1 and the network 2. As a result, it becomes possible,for example, to prevent unnecessary location registration fromoccurring, to reduce traffic with the network 2, and to reduce batterypower consumption of the portable terminal device 1.

Moreover, as described above, in the case where the portable terminaldevice 1 moves between areas in such a way as to cross over RATs, theterminal-specific identifier to be specified for the locationregistration requesting message, which the portable terminal device 1sends to the network 2, is set with an appropriate value, depending onwhether ISR is active or inactive. Therefore, crossing over areas ofdifferent RATs, the network 2 can take over location registrationinformation of the portable terminal device 1, by way of preventingbeforehand a situation of conflict with respect to status of ISR fromarising between the portable terminal device 1 and the network 2, evenwhen the portable terminal device 1 moves into an area of a differentRAT, and carries out location registration there. Accordingly, thereremains no chance to receive an unnecessary request on releasingregistration from the network 2. As a result, it becomes possible toprotect a call connection supplied to a user from being interrupted bysuch an unnecessary request on releasing registration from the network2.

The invention claimed is:
 1. A User Equipment (UE) comprising: atransmitter configured to send a Tracking Area Update (TAU) Requestmessage; a receiver configured to receive a TAU Accept message aftersending the TAU Request message; and a controller configured to set aTemporary Identity used in Next update (TIN) to Globally UniqueTemporary Identifier (GUTI) in a case in which (1) the TIN is currentlyset to Packet Temporary Mobile Subscriber Identity (P-TMSI), (2) the TAUAccept message contains an indication of Idle mode Signaling Reduction(ISR) being activated, and (3) a periodic routing area update timer hasalready expired.
 2. The UE according to claim 1, wherein setting of theTIN to P-TMSI corresponds to the ISR being deactivated.
 3. The UEaccording to claim 1, wherein setting of the TIN to GUTI corresponds tothe ISR being deactivated.
 4. The UE according to claim 1, furthercomprising a transmitter configured to transmit a Routing Area Update(RAU) request including “P-TMSI from GUTI” as Old P-TMSI, in a casewhere the TIN is set to GUTI.
 5. A paging processing method, comprising:sending, by a User Equipment (UE), a Tracking Area Update (TAU) Requestmessage; receiving, by the UE, a TAU Accept message after sending theTAU Request message; and setting a Temporary Identity used in NextUpdate (TIN) to Globally Unique Temporary Identifier (GUTI) in a case inwhich (1) the TIN is currently set to Packet Temporary Mobile SubscriberIdentity (P-TMSI), (2) the TAU Accept message contains an indication ofIdle mode Signaling Reduction (ISR) being activated, and (3) a periodicrouting area update timer has already expired.
 6. The method accordingto claim 5, wherein setting of the TIN to P-TMSI corresponds to the ISRbeing deactivated.
 7. The method according to claim 5, wherein settingof the TIN to GUTI corresponds to the ISR being deactivated.
 8. Themethod according to claim 5, further comprising transmitting a RoutingArea Update (RAU) request including “P-TMSI from GUTI” as Old P-TMSI, ina case where the TIN is set to GUTI.